Working up gases containing hydrocarbons in electric arcs



Muck 23,1937. R g AN ET AL I 2,074,530

WORKING UP GASES CONTAINING HYDROCARBONS IN ELECTRIC ARCS Filed July so, 1932 VENTORS PA a. flo sn 'ma Him 10H Scrimma- WPLW A ORNEYS Patented Mar. 23, 1937 UNITED STATES-'1 PATE WORKING UP GASES CONTAINING HYDRO- OARBONS INELECTBIC ARCS Lndwigshafen-on-the-Rhine, Robert Stadlcr, Ziegelhausen, and

Paul Banmann,

NT oFFIcI-J Heinrich Schilling, Lndwigshafen-on-the-Bhin Germany,

assignors to I. G. Farbenindnstrie Aktiengesellschaft, Frankfort on the Main,

Germany Application July 80, 1982, Serial No. 626,472 In Germany A 4, 1931 13 Claims. ((1204-31) The present invention relates to improvements in and apparatus for working up gases containing hydrocarbons in electric arcs.

It is already known that deposits of carbon on the electrodes and on the walls of the reaction 15 We have now found that even highly concen-j trated. hydrocarbons or gases entirely consisting of hydrocarbons can be treated in electric arcs and in particular converted into final gases rich in acetylene in a simple manner without the 20 said precautions and while avoiding the deposi tion of carbon to a great extent, by causing the striking points of the electric arcs to rapidly move on the surfaces-of both. electrodes. By imparting to the striking points a rapid movement 5 the deposition of carbon black in the electric arcs and on the electrodes is prevented to a farreaching extent, so thatvgases containing large amounts of carbon in the unit of space, as for example highly concentrated propane, can be worked up in a manner free from objection even without anydilution and without special addition of protective gas at the electrodes. The speed of movement of the striking points of the arcs is selected great enough to prevent any great local 5 heating, for example-up to about 400 C., in the neighbourhood thereof. The velocity of the striking points as a rule should be greater than 5 centimeters per second and preferably greater than 20 centimeters per second. The striking issues from the electrode into the gas space. Any

0 invention liquid hydrocarbons suspended in the form of mists in carrier gases, such as hydrogen, or brown-coal dust maybe treated-in the described manner. The process according to the present invention is, of course, not restricted to 55 highly concentrated hydrocarbons or gases conpoint "is the place at which the electric current sisting entirely of hydrocarbons, but also less concentrated hydrocarbons, for example those containing substantial amounts of an inert gas, such as nitrogen or hydrogen as for example coke oven gas maybe employedas initial materials.

The said gaseous and vaporous and suspended liquid hydrocarbons are hereinafter referred toas vaporized hydrocarbons, I

Natural gas, coal gas, gases arising from the lowtemperature carbonization of coals or lignites, waste gases from the destructive hydrogenation of coals, tars and mineral oils or other gases comprising suitable vaporized hydrocarbons may be employed as initial materials.

In particular with gases rich in hydrocarbons, especially those of higher molecular weightthan methane, a rapid movement of the striking points shouldbe set up. In these cases the velocity of these striking pointsis preferably not lower than 20 centimeters per second while with gases containing substantial amounts of inert gases, such as coke oven gas also lower velocities, as for example between 5 and centimeters per second, may be employed.

The'surface of the electrodes which is played upon by the striking points of the arcs should not be selected too small. The most suitable size of the said surface depends on the heat conducting properties and-the cooling action of the flowing gases. This size must be the greater the smaller is the capacity of conducting heat and the smaller is the cooling action of the flowing gases. The movement. of the striking points of the arcs may be effected, for example by electromagnetic means, or mechanically, as for example by'means of a stream of gas; in the latter case the gas to be treated or other gases such as nitrogen or hydrogen may be employed for this purpose. The electrodes are preferably constructed in the form of tubes. If the speed of movement of the striking point of the arcs is great enough any previous deposition of carbon black on the electrodes disappears entirely and the formation of carbon black in the electric arc itself ceases almost enti'rely. when the said speed of movement is sufflciently great electrodes composed for example of carbon or graphite even diminish in size.

The nature of this invention will be further described with reference to the accompanying drawing which illustratesdiagrammatically an electric arc reaction chamber suitable for carrying out the process accordingto this invention, but the invention is not restricted to the particular arrangement shown.-

L is the electric are, E the electrode, J the insulation, G1 and G: the gas inlets, F the tube which is connected to the earth and in which the electric arc burns, A is the gas outlet and S the voltage supply.

A part of the gas to be-treated is tangentially tangential introduction into the system the gas has a whirling motion as it passes through the' arc. By varying the amount of gas introduced at G2 it is possible to increase the voltage consumption of the electric are within wide limits, as for example up to 50 per cent. The curve in the electrode E (shown in dotted lines) indicates how the electrode burns after use for long periods of time. The gas supplied at G1 is tangentially introduced into the cylindrical space 0.

In order to operate electric arc reaction chambers, in which it is desired to prevent the growing of the electrode in the sense of the present invention, alternating current or rectified alternatlng current is especially suitable because after the temporary suspension of the discharge on the electrode the electric arc strikes again from a different place on the electrode.

The electric arc reaction chamber of the type hereinbefore described has the great advantage that in the working up of carbonaceous substances, such as the preparation of acetylene, the deposition of carbon black in the electric arcs and and on the electrodes is so far prevented by moving the striking points of the arcs that gases containing large amounts of carbon per cubic meter, as for example propane, can be worked up in a manner free from objection even without any di- 40 lution and without special addition of protective gas at the electrodes. If gases not participating in the reaction are supplied in order to cause the movement of the striking points of the electric are they may act also as protective gases. But

it is a great advantage of the present invention that this dilution is not necessary and that consequently the energy emciency is very good.

The following example will further illustrate the nature of this invention but the invention is not restricted to this example.

Example 80 cubic meters per hour of a 95 per cent propane are worked up in an electric arc reaction chamber the voltage-conducting electrode of 0 ograms of carbon black are obtained per hour.

The energy yield is from to liters of acetylene per kilowatt-hour. The reaction chamber must be shut off after a short time by reason of short circuit caused by the carbon deposited on the electrode.

If the stick-shaped electrode be replaced by a hollow electrode as shown in the accompanying drawing and a part of the gas to be treated which may vary between 1 to 15 per cent be led therethrough, whereby the striking point of the arc is set in rapid movement, so that it rotates about times per minute, the energy consumption of the arc rises from 100 to kilowatts. The final gas contains from 14 to 16 per cent, of acetylene. The energy yield amounts to from 120 to liters of acetylene per kilowatt-hour. After several hours the operation is still free from objection. The electrode carries no deposits and the content of carbon black in the gas is scarcely noticeable.

What we claim is:

1. In the production of acetylene by treatment of a gaseous hydrocarbon in the electric arc the step of continuously causing the striking points of the electric arc to rapidly move on the surfaces of both electrodes to or from different points on each electrode.

2. In the production of acetylene by treatment of a gaseous hydrocarbon in the electric are set up by an alternating current the step of continuously causing the striking points of the electric arc to rapidly move on the surfaces of both electrodes to or from different points on each electrode.

3. In the production of acetylene by treatment of a gaseous hydrocarbon in the electric are set up by a rectified alternating current the step of continuously causing the striking points of the electric arc to rapidly move on the surfaces of both electrodes to or from different points on each electrode. I

4. In the production of acetylene by treatmen of a vaporized hydrocarbon in an electric are set up between hollow electrodes the step of causing the striking points of the electric arc to rapidly move on the surfaces of both electrodes.

5. In the production of acetylene by treatment of a gaseous hydrocarbon in the electric are set up by an alternating current between hollow electrodes the step of causing the striking points 7. In the production of acetylene by treatment of a vaporized hydrocarbon in an electric are set up between hollow electrodes the step of causing the striking points of the electric arc to move on the surfaces of both electrodes with a velocity of more than 5 centimeters per second.

8. In the production of acetylene by treatment of a vaporized hydrocarbon in an electric are set up between hollow electrodes the step of causing the striking points of the electric arc to move on the surfaces of both electrodes with a velocity of more than 20 centimeters per second.

9. In the production of acetylene by treatment of a vaporized hydrocarbon in an electric are set up between hollow electrodes, the step of causing the striking points of the electric arc to rapidly move on the surfaces of both electrodes by tangentially introducing the gas into one of the hollow electrodes, thereby causing the gas to traverse the arc in a whirling motion.

10. In the production of acetylene by treatment of a gaseous hydrocarbon in the electric are set up by an alternating current between hollow electrodes; the step of causing the striking points of the electric arc to rapidly move on the surfaces of both electrodes by tangentially introducing the gas into one of the hollow electrodes, thereby causing the gas to traverse the arc in a whirling motion.

11. In the production of acetylene by treatment of a gaseous hydrocarbon in the electric are set up by a rectified alternating current between hollow electrodes. the step of causing the striking points of the electric arc to rapidly move on the surfaces of both electrodes by tangentially introducing the gas into one of thehollow electrodes, thereby causing the gas to traverse the arc in a whirling motion.

10 of causing the striking points of the electric arcs to rapidly move on the surfaces 01' both electrodes by passing a whirling stream 0! gas through the electrodes.

13. In the production of acetylene by treatment or a vaporized hydrocarbon in an electric are set up between hollow electrodes, the step 01' causing the striking points of the electric arc to rapidly move on the surfaces of both electrodes by passing part of the vaporized hydrocarbons in the form of a whirling stream through the electrodes.

PAULBAUMANN. ROBERT STADLER. HEINRICH SCHILLING. 

